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Recombinant oncotoxin AR209 (anti-P185erbB-2) diminishes human prostate carcinoma xenografts
N Skrepnik1, A W Zieske, J C Bravo
1Department of Biochemistry and Molecular Biology, Stanley S. Scott Cancer Center, Louisiana State University Medical Center, New Orleans 70112, USA.
Purpose:
Prostate cancer is the most common malignancy of males in the United States. Although the overall survival rate for early stage prostate cancer is good, if cancer recurs following curative therapies there is no adequate salvage therapy. Systemic chemotherapy has never been associated with any meaningful improvement in overall survival or overall objective benefit. There is a need to develop novel therapies for prostate cancer.
Materials And Methods:
Two prostatic cancer cell lines, DU-145 and PC-3, were grown as subcutaneous xenografts in athymic nude mice. The recombinant oncotoxin AR209, formerly OLX-209 [e23(Fv)PE38KDEL]), has the specificity of an anti-p185erbB-2 antibody contained within a single-chain antibody domain (e23Fv) coupled to a portion of the Pseudomonas exotoxin A (PE38KDEL). Using Western blot analysis, the cell lines were shown to express p185erbB-2. The mice received either 3 i.v. injections, one every 2 days, of the recombinant oncotoxin AR209 or PBS, or were implanted with osmotic pumps that delivered a constant s.c. amount of AR209 or PBS.
Results:
The oncotoxin was effective in reducing the size of s.c. prostatic xenografts in athymic nude mice. The data demonstrated that small tumors (<200 mm.3) were effectively reduced in size. However, larger tumors (>500 mm.3) were not effectively diminished.
Conclusions:
This study provides preliminary evidence for the utility of a recombinant oncotoxin in the treatment of prostate carcinoma. Recombinant oncotoxins may be an effective clinical addition for the management of metastatic prostate lesions in patients treated with conventional therapy.
Insights
A novel recombinant oncotoxin effectively reduced small prostate tumors in mice. Larger tumors were less responsive, indicating potential for targeted therapy in advanced prostate cancer treatment.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Prostate cancer is a leading malignancy in the US.
- Recurrent prostate cancer lacks effective salvage therapies.
- Current systemic chemotherapy offers limited survival benefits.
Purpose of the Study:
- To investigate the efficacy of a novel recombinant oncotoxin, AR209, against prostate cancer.
- To evaluate AR209's potential as a new therapeutic agent for prostate carcinoma.
Main Methods:
- Prostate cancer cell lines (DU-145, PC-3) were grown as subcutaneous xenografts in nude mice.
- Mice received intravenous injections or subcutaneous osmotic pump delivery of AR209 or PBS.
- Western blot analysis confirmed p185erbB-2 expression in cell lines.
Main Results:
- The recombinant oncotoxin AR209 significantly reduced the size of small subcutaneous prostate tumors (<200 mm³).
- Larger tumors (>500 mm³) showed limited response to AR209 treatment.
- AR209 demonstrated oncotoxin activity against xenografts expressing p185erbB-2.
Conclusions:
- Preliminary evidence supports the utility of recombinant oncotoxin AR209 for prostate carcinoma treatment.
- Recombinant oncotoxins may offer a new therapeutic option for metastatic prostate lesions.
- Further research is warranted to optimize AR209 therapy for prostate cancer management.